(1) Field of the Invention
The present invention concerns a process for separating a component of intermediate permeability from a gaseous mixture. The invention is particularly applicable to the removal of CO.sub.2 from a hydrogen-carbon dioxide (CO.sub.2)-carbon monoxide(CO) mixture.
(2) Description of Prior Art
The standard technique for carrying out such removal consists in washing the mixture, either by means of amines (chemical washing), or by means of products having an absorption "physical behavior". This leads to substantial investment and consumption of energy.
The document US.-A- 3.250.080 describes a process of separating a gaseous mixture by diffusion and fractionation utilising a train of permeation cells mounted in series on the high pressure side as well as on the low pressure side and a portion of the residual gas from the high pressure outlet end is circulated towards the low pressure inlet end of the cells.
Such equipment is particularly complex.
The documents G.B.-A- No. 2.053.021 and EP-A- No. 0.029.600 also describe systems for separating a gas derived from a high pressure compartment of a membrane separator towards the low pressure compartment There is no treatment during this recycling.